NEW YORK (AP)  United Airlines says domestic flights are on the move again after being grounded Sunday because of a computer problem.

Company spokeswoman Maddie King says the “IT issue” that initially caused the ground stop has been resolved and flights are resuming, but customers may experience additional delays. She didn’t give any more details.

It was not immediately clear how many flights were affected. The ground stop lasted about 2 ½ hours.

Chicago-based United Airlines and United Express operate more than 4,500 flights a day to 339 airports across five continents.